public class Child extends Base {
    public static int s;
    private int a;
    static {
        System.out.println("子类静态代码块,s"+s);
        s = 10;
    }
    {
        System.out.println("子类实例代码块，a"+a);;
        a = 10;
    }
    public Child(){
        System.out.println("子类构造方法,a:"+a);
        a = 20;
    }
    protected void step(){
        System.out.println("childs" + s + ",a:"+ a);
    }
}